I built this Mini-Scamp
microcomputer in 1976 (I think). It was a Dick Smith Electronics
(DSE) kit from the days when Dick Smith actually owned and ran
Dick Smith electronics. The design was published in "Electronics
Australia" (EA). It was based on the SC/MP CPU from National
Semiconductors. It boasted a massive 256 bytes of RAM (yes Bytes
not Kbytes) - this was 4 times more than the earlier model. It
had no ROM or EEPROM of any kind. The complete user inferface is
visible in the photo above. Binary code was entered into the RAM
by dialing up the data byte and address in binary using toggle
switches. Pressing the deposit button stored the byte in memory.
The LEDs showed the current contents of the memory location.
After the program was enter in this manner one of the switches on
the right was flipped from DMA to run mode and the micro executed
the code (the other switch was power). The micro could display
bytes on the LEDs and read bytes from the data switches - the
request LED was there to signal the user to enter a byte and
press deposit. No problem with Y2K bugs, viruses or hackers
here.I almost built a EDUC-8 - a computer that didn't use a
micro-processor, you built the processor out of logic chips.
There are still people around who get a kick out of this sort of
thing - and amateurs who design and build there own processors as
I hope to discuss later in this page.I did not manage to do
much with the SCMP, it played a few tunes out of the speaker I
added and it flashed random numbers on it's LED display - but it
was a good start into the world of micro-computers.....

The 2650 - 1979

After the SCMP came the sygnetics 2650. I stayed with this
processor for many years and many generations of hardware. My
first 2650 was another kit probably EA and DSE as above. From
memory it had up to 7K of RAM and 1 K of rom. It ran from a 110
baud serial key board, talked to a 110 baud serial video terminal
unit (VDU) and could load and save programs onto a cassette again
at 110 baud. Compared to the SCMP this was heaven. The
keyboard VDU and cassette were all kit built and I used a large
valve TV for the display.Then it started to grow. The EA cpu
card was replaced by a KT9500 card and then by an S100 based
card.The serial VDU was replace with a memory mapped VDU
(that could do chunky graphics). The cassette system was replace
by a homebrew "non return to zero" (NRZ) interface and
a homebrew tape file format. The NRZ interface used software
driven phase encoding (aka Manchester encoding). Western digitial
released a single chip floppy disk controller (wd-1770??) and a
(now) friend of mine Mike Van Emmerik
and a friend of his (Ron Harris) designed a floppy disk inferface
and a DOS for the 2650. I wire wrapped a controller borrowed
money off my mother to buy a drive (around $600 for a 100K floppy
drive) and out went the tape. The floppy controller was single
denisty (for those who still know what that means). Around 1982
WD released a double density controller (3 chip set), now it was
my turn to design a controller card - and this was it.

I had you do some major work on the DOS to get it to work
with this card. The CPU only ran at 1 megaherz and wasn't fast
enough to pole the controller as it did previously this was
because of the higher transfer rates for double density and/or 8
inch drives. There were other problems as well while formating
the longer tracks.My first printer was a baudot printer. The
type the post office used for sending telegrams. It weighed
slightly less than I did and the whole house shook we it
printed. Baudot code was a 5 bit code send at 50 baud - it would
print around 5 cps. I had a number of printers over the
years including a Burrows Teller terminal I hacked into.

One of the programs I wrote when I first got a VDU that
could do crude graphics was a game I called UFO - very crude
- it was around 1979. Anyhow I got this email a few months
back...

"...every few seconds a UFO
will traverse the screen, on the base line is drawn the lid of a
missile silo" I have a listing in front of me, circa 1979
and written by E.Matejowsky. I'm figuring thats you, and thought
you'd get a kick out of learning someone nearly 20 years later is
casually browsing through the listing. Cheers A

I'm a collector of old computers - anything homebrew or early
home and game computers (not IBM!!) and this is one of the ways I
build up contacts and track down old machines, programs and
documentation. This listing was saved from the dumpster some
number of years ago by an electronics guy, and when he decided to
sell his old computer (to me!!), I asked if there was anything of
this sort he would like to send to a good home. Having found the
listing I thought it would be both fun and possibly productive
attempting to find the original authors of some of these
programs. I'm persistant like that ;) So, a few net searches
(just a couple of minutes actually - I wish I could make it sound
more sherlock-holmesish but it was simple) and I found you :)

Of course, your name wasn't that hard to track down - but I've
also found some of the other authors of these programs, too. The
reactions have been fun, including "well bugger me dead!!"

Cheers A

Until 1982 virtually all the programming I did was in
assembler. I got interested in a language called FORTH after
spending some time on Great Keppel Island with Peter Milford and
his friends who were forth fanatics. Later I was given a FORTH
compiler for the 2650 by a friend -the late Dr Dan Hamilton and
slowly got to understand this odd language. Around this time I
resigned from my job in the photographic industry and tried to
make a living amongst other things by fixed video games,
unfortunately I didn't see the money for much of what I did and
needed to find something else.Another friend, Ed Hancock
suggested I design a boat alarm and I did so. I figured the 2650
was too expensive @ $25 each and instead used a 6502 @ $5. I
wrote a conventional 2 pass 6502 cross assembler in 2650 forth
and programmed the 2K eproms for the alarm in the card show
above. Needless to say it flopped we sold a grand total of one.
We called the system Compu-guard. Around this time I met a guy
named Terry Ryan who was Oz inventor of the year for his
prop-scan propellor pitch measuring device. I wrote some code for
him for a navy contract he had (sort of). He had a dream of
setting up an innovations centre on the Gold Coast. This would
have been great but Dan found me a job at the University of
Queensland and I didn't get involved with the proposed centre.- a
pity you can't do everything.